Many applications require memory having quick access times, but at an expense of considerable energy consumption. Examples are cache memories within integrated circuits, central processing units or communication devices or modems, such as modems with 2G/3G/LTE support. Static RAM (SRAM) is fast and has short read and write access times (usually <1 ns) while the energy consumption or the leakage current required to maintain the stored information can be comparatively high. Other memories may have a lower leakage current but with longer read/write access times.